Friday, April 30, 2021

Excess mortality rates since 2000 in the US compared with Europe.

Interesting, from Preston and Vierboom. Just the numbers, no commentary on the causes (mainly opioid crisis?).
We use three indexes to identify how age-specific mortality rates in the United States compare to those in a composite of five large European countries since 2000. First, we examine the ratio of age-specific death rates in the United States to those in Europe. These show a sharp deterioration in the US position since 2000. Applying European age-specific death rates in 2017 to the US population, we then show that adverse mortality conditions in the United States resulted in 400,700 excess deaths that year. Finally, we show that these excess deaths entailed a loss of 13.0 My of life. In 2017, excess deaths and years of life lost in the United States represent a larger annual loss of life than that associated with the COVID-19 epidemic in 2020.
Age-specific comparisons of US and European mortality: 2000, 2010,2017. Source: HMD (12). (A) Ratio of US age-specific death rate to Europeanstandard. (B) Change in US death count if US had European age-specificdeath rates. (C) Years of life lost based on US life expectancies and US/European comparisons of age-specific death rates

Wednesday, April 28, 2021

Embracing diversity can disadvantage minorities

From Starck et al.:  


There are numerous reasons why institutions of higher education may choose to embrace diversity. A common rationale sanctioned by the US Supreme Court is that diversity provides compelling educational benefits and is thus instrumentally useful. We show that such instrumental rationales are the predominant rationale for diversity efforts in American higher education, are preferred by White Americans and not by Black Americans, that they are expected to advantage White Americans, and that they correspond to greater racial disparities in academic achievement. Overall, these findings suggest that the rationales behind universities’ embrace of diversity have nonlegal consequences that should be considered in institutional decision making.
It is currently commonplace for institutions of higher education to proclaim to embrace diversity and inclusion. Though there are numerous rationales available for doing so, US Supreme Court decisions have consistently favored rationales which assert that diversity provides compelling educational benefits and is thus instrumentally useful. Our research is a quantitative/experimental effort to examine how such instrumental rationales comport with the preferences of White and Black Americans, specifically contrasting them with previously dominant moral rationales that embrace diversity as a matter of intrinsic values (e.g., justice). Furthermore, we investigate the prevalence of instrumental diversity rationales in the American higher education landscape and the degree to which they correspond with educational outcomes. Across six experiments, we showed that instrumental rationales correspond to the preferences of White (but not Black) Americans, and both parents and admissions staff expect Black students to fare worse at universities that endorse them. We coded university websites and surveyed admissions staff to determine that, nevertheless, instrumental diversity rationales are more prevalent than moral ones are and that they are indeed associated with increasing White–Black graduation disparities, particularly among universities with low levels of moral rationale use. These findings indicate that the most common rationale for supporting diversity in American higher education accords with the preferences of, and better relative outcomes for, White Americans over low-status racial minorities. The rationales behind universities’ embrace of diversity have nonlegal consequences that should be considered in institutional decision making.

Monday, April 26, 2021

Sensitivity to geometric shape: A putative signature of human singularity

From Sablé-Meyer et al.:
Among primates, humans are special in their ability to create and manipulate highly elaborate structures of language, mathematics, and music. Here we show that this sensitivity to abstract structure is already present in a much simpler domain: the visual perception of regular geometric shapes such as squares, rectangles, and parallelograms. We asked human subjects to detect an intruder shape among six quadrilaterals. Although the intruder was always defined by an identical amount of displacement of a single vertex, the results revealed a geometric regularity effect: detection was considerably easier when either the base shape or the intruder was a regular figure comprising right angles, parallelism, or symmetry rather than a more irregular shape. This effect was replicated in several tasks and in all human populations tested, including uneducated Himba adults and French kindergartners. Baboons, however, showed no such geometric regularity effect, even after extensive training. Baboon behavior was captured by convolutional neural networks (CNNs), but neither CNNs nor a variational autoencoder captured the human geometric regularity effect. However, a symbolic model, based on exact properties of Euclidean geometry, closely fitted human behavior. Our results indicate that the human propensity for symbolic abstraction permeates even elementary shape perception. They suggest a putative signature of human singularity and provide a challenge for nonsymbolic models of human shape perception.

Friday, April 23, 2021

What coffee does to body and mind

I am completely dependent on coffee, starting every morning with this stimulant and continuing small sips until a lunchtime cappuccino terminates my consumption for the day. Thus I found this article by Michael Gross on the history of caffeine consumption by humans and animals completely fascinating. I'll pass on just the first few paragraphs to whet your appetite, and let you download the complete article if you would like to continue reading on to Gross's discussion of coffee's effects on brain and mind. 


Johann Sebastian Bach never wrote an opera, simply because his employers had no use for one and kept him busy with other things. An intriguing glimpse at what the world missed is afforded by the secular cantata Schweigt stille, plaudert nicht (BWV 211), a half-hour mini-opera about a young woman addicted to coffee and her father trying to persuade her to quit. Bach is thought to have composed the work known as the ‘coffee cantata’ on the words of Picander in the 1730s, when he was the St Thomas Cantor at Leipzig and conducted an orchestra at the Café Zimmermann as a sideline.
It dates from a time when coffee was a new-fangled fashion craze gradually spreading across Europe. From myth-shrouded origins in the kingdom of Sheba, today’s Yemen or Ethiopia, the culture of making and drinking coffee expanded across the Arabian Peninsula and into the Ottoman Empire, reaching its capital, Istanbul, in 1554. After the Ottoman advance into Europe was stopped just outside Vienna in 1683, the victorious Austrians confiscated the coffee supplies of the fleeing Turks and used them to launch their legendary coffee-house culture, which spread across Europe. An independent early entry route was provided by Venetian traders.
From the beginnings of this spread there had been attempts by religious leaders, in both Islamic and Christian societies, to ban coffee, as they found its powerful stimulating effect suspicious. Thus, the lively conflict in Bach’s coffee cantata reflected a very real debate that must have taken place many times between lovers of the dark brew and authorities suspicious of its effects.

Wednesday, April 21, 2021

Ancient Greece's Army of Lovers

This post is under MindBlog's "random and curious stuff" category. A piece by Daniel Mendelsohn in The New Yorker:
Comprising a hundred and fifty male couples, Thebes’s Sacred Band was undefeated until it was wiped out in 338 B.C. In the nineteenth century, the mass grave of the men was found.
Image courtesy Hellenic Ministry of Culture and Sports, Directorate of the Management of the National Archive of Monuments, Department of the Historical Archive of Antiquities and Restorations
In June, 1818, during a visit to central Greece, a young English architect named George Ledwell Taylor went out riding with some friends in order to explore the ruins of an ancient town called Chaeronea. As Taylor’s party neared its destination, his horse took a “fearful stumble,” as he later recalled, on a stone in the roadway; on further inspection, he saw that the stone was, in fact, part of a sculpture. Energetic digging eventually revealed an animal head nearly six feet high—or, as Taylor put it, a “colossal head of the Lion.”
That definite article and the capital “L” are crucial. Taylor realized that he had uncovered a famous monument, mentioned in some historical sources but since lost, known as the Lion of Chaeronea. The Englishman had been studying a work called “The Description of Greece,” by Pausanias, a geographer of the second century A.D., which states that the gigantic figure of the sitting animal had been erected to commemorate a remarkable military unit that had perished there. The lion, Pausa­nias surmised, represented “the spirit of the men.”
The unit to which those men belonged was known as the Sacred Band. Comprising three hundred warriors from the city of Thebes, it was among the most fearsome fighting forces in Greece, undefeated until it was wiped out at the Battle of Chaeronea, in 338 B.C.—an engagement during which Philip of Macedon and his son, the ­future Alexander the Great, crushed a coalition of Greek city-states led by Athens and Thebes. Scholars see Chaeronea as the death knell of the Classi­cal Era of Greek history.
Others might find the story interesting for different reasons. Not the least of these is that the Band was composed entirely of lovers: precisely a hundred and fifty couples, whose valor, so the Greeks thought, was due to the fact that no man would ever exhibit cowardice or act dishonorably in front of his beloved. In Plato’s Symposium, a dialogue about love, a character remarks that an army made up of such lovers would “conquer all mankind.”
Sixty years after George Taylor’s horse stumbled, further excavations revealed a large rectangular burial site near the Lion. Drawings that were made at the site show seven rows of skeletons, two hundred and fifty-four in all. For “The Sacred Band” (Scribner), a forthcoming book by the classicist James Romm, the illustrator Markley Boyer collated those nineteenth-century drawings to produce a reconstruction of the entire mass grave. Black marks indicate wounds. A number of warriors were buried with arms linked; if you look closely, you can see that some were holding hands. ♦

Monday, April 19, 2021

Gamma-frequency oscillations link different brain regions during learning.

Fernández-Ruiz et al. demonstrate that specific, projected gamma-frequency oscillation patterns dynamically engage functionally related cell assemblies across brain regions in a task-specific manner. I pass along their entire structured abstract:  


Learning induces a dynamic reorganization of brain circuits but the neuronal mechanisms underlying this process are not well understood. Interregional gamma-frequency oscillations (~30 to 150 Hz) have been postulated as a mechanism to precisely coordinate upstream and downstream neuronal ensembles, for example, in the hippocampal system. The lateral (LEC) and medial (MEC) entorhinal cortex receive inputs from two distinct streams of cortical hierarchy (the “what” and the “where” pathways) and convey these neuronal messages to the hippocampus. However, the mechanisms by which such messages are packaged and integrated or segregated by hippocampal circuits had yet to be explored.
Neuronal assemblies firing within gamma time frames in an upstream region can most effectively discharge their downstream partners. This gamma-time-scale organization appears essential for physiological functions because manipulations that impair precision timing of spikes in the hippocampus often affect behavior. However, direct support for distinct gamma-frequency communication in appropriate behavioral situations is missing. To bring physiological operations closer to behavior, we designed “spatial” and “object” learning tasks and examined the selective engagement of gamma-frequency communication between the MEC and LEC inputs and their target neuronal assemblies in the hippocampal dentate gyrus. We combined these correlational observations with optogenetic perturbation of gamma oscillations in LEC and MEC, respectively, to test their roles in pathway-specific neuronal communication and learning.
During spatial learning, fast gamma (100 to 150 Hz) oscillations synchronized MEC and dentate gyrus and entrained predominantly granule cells. During object learning, slow gamma (30 to 50 Hz) oscillations synchronized LEC and dentate gyrus and preferentially recruited mossy cells and CA3 pyramidal neurons, suggesting task-specific routing of MEC and LEC messages in the form of gamma-cycle-spike packets of selected cell types. The low- and high-frequency gamma sub-bands were dominant in the outer and middle third of the dentate molecular layer, respectively, and their amplitude maxima were locked to different phases of theta oscillations.
Gamma frequency optogenenetic perturbation of MEC and LEC led to learning impairments in a spatial and object learning task, respectively. In the same animals, the dentate layer–specific low- and high-frequency gamma sub-bands and spike-gamma LFP coupling were selectively reduced, coupled with deterioration of spatial and object-related firing of dentate neurons.
These findings demonstrate that distinct gamma-frequency-specific communication between MEC and LEC and hippocampal cell assemblies are critical for routing task-relevant information, and our selective gamma-band perturbation experiments suggest that they support specific aspects of learning. We hypothesize that sending neuronal messages by segregated gamma-frequency carriers allows a target “reader” area to disambiguate convergent inputs. In general, these results demonstrate that specific projected gamma patterns dynamically engage functionally related cell assemblies across brain regions in a task-specific manner.

Friday, April 16, 2021

Vision: What’s so special about words?

Readers are sensitive to the statistics of written language. New work by Vidal et al. suggests that this sensitivity may be driven by the same domain-general mechanisms that enable the visual system to detect statistical regularities in the visual environment. 


• Readers presented with orthographic-like stimuli are sensitive to bigram frequencies 
• An analogous effect emerges with images of made-up objects and visual gratings 
• These data suggest that the reading system might rely on general-purpose mechanisms 
• This calls for considering reading in the broader context of visual neuroscience
As writing systems are a relatively novel invention (slightly over 5 kya), they could not have influenced the evolution of our species. Instead, reading might recycle evolutionary older mechanisms that originally supported other tasks and preceded the emergence of written language. Accordingly, it has been shown that baboons and pigeons can be trained to distinguish words from nonwords based on orthographic regularities in letter co-occurrence. This suggests that part of what is usually considered reading-specific processing could be performed by domain-general visual mechanisms. Here, we tested this hypothesis in humans: if the reading system relies on domain-general visual mechanisms, some of the effects that are often found with orthographic material should also be observable with non-orthographic visual stimuli. We performed three experiments using the same exact design but with visual stimuli that progressively departed from orthographic material. Subjects were passively familiarized with a set of composite visual items and tested in an oddball paradigm for their ability to detect novel stimuli. Participants showed robust sensitivity to the co-occurrence of features (“bigram” coding) with strings of letter-like symbols but also with made-up 3D objects and sinusoidal gratings. This suggests that the processing mechanisms involved in the visual recognition of novel words also support the recognition of other novel visual objects. These mechanisms would allow the visual system to capture statistical regularities in the visual environment. We hope that this work will inspire models of reading that, although addressing its unique aspects, place it within the broader context of vision.

Wednesday, April 14, 2021

Useful Delusions

I want to pass on to MindBlog readers some background information on the recent book "Useful Delusions: The Power and Paradox of the Self-Deceiving Brain" by Shankar Vedantam, host of NPR’s “The Hidden Brain,” and science writer Bill Mesler. It was compiled by a member of the four person program committee of the Austin Rainbow Forum discussion group to which I belong.
This Hidden Brain podcast interview with Shankar Vedantum is a great resource for those up to the challenge of sitting in a comfortable chair for an hour listening to a great conversation while enjoying a pleasant beverage.
And here are a few alternatives for the listening challenged:
A book excerpt at the Hidden Brain website.
And, book reviews from The New York Journal of Books, and The Wall Street Journal.

Monday, April 12, 2021

Why does passion matter more in individualistic cultures?

Tsai does an interesting commentary  (open source) on work noted in MindBlog's recent post on an article by Li et al.  Some clips:

Our research finds that, because achieving independence requires increased arousal and action, cultures that foster these goals value high-arousal positive states like passion, excitement, and enthusiasm. In contrast, because achieving interdependence requires decreased arousal and action, cultures that foster these goals value low-arousal positive states like calm, peacefulness, and balance.
These ideals matter because people use them to judge their own feelings, and, perhaps even more importantly, to judge the feelings of others. For instance, because European Americans value excitement more than Hong Kong Chinese, they rate “excited” faces (with broad toothy smiles) as much friendlier and warmer than “calm” faces (with closed smiles), compared to Hong Kong Chinese. And, because European Americans perceive excited (vs. calm) faces as friendlier and warmer, they share more money with excited vs. calm partners in economic games (e.g., the Dictator Game), compared to East Asians.
Experiencing and expressing cultural ideals can have life-altering consequences in the real world. When deciding whom to lend to on a web-based microlending platform (, people from countries with an excitement ideal loaned more to borrowers who had “excited” smiles in their profile photos and less to borrowers who had “calm” smiles. In a business setting, when selecting an intern, European Americans viewed the “ideal applicant” as being more excited (vs. calm), and chose more excited (vs. calm) applicants than Hong Kong Chinese did. Even in health settings, European Americans chose excitement-focused physicians who promoted dynamic lifestyles (vs. calm-focused physicians who promoted relaxing lifestyles) more than Hong Kong Chinese did. Interestingly, European Americans also recalled and adhered to the recommendations of the excitement- versus calm-focused physician more than East Asian Americans did. These findings suggest that people may also be more receptive to the advice and feedback of people who express their cultural ideal. the context of a European American focus on passion, calm East Asian Americans are often inaccurately judged to be “cold” and “stoic” . This may explain why, compared to European Americans, East Asian Americans are less likely to be promoted to top leadership positions, a problem often described as “the Bamboo Ceiling”. But this might be avoided if teachers, employers, and other decision makers in individualistic cultures understood that in many cultures — as illustrated by the findings of Li et al. — passion matters less. Instead of passion, people are finding, following, and fueling calm, balance, and the other affective states that their cultures value more.

Friday, April 09, 2021

The Psychology of Fake News

Pennycook and Rand do a fascinating open source article in Trends in Cognitive Science on the psychology of fake news.  Their highlights and summary: 

Recent evidence contradicts the common narrative that partisanship and politically motivated reasoning explain why people fall for 'fake news'. 
Poor truth discernment is linked to a lack of careful reasoning and relevant knowledge, as well as to the use of familiarity and source heuristics. 
There is also a large disconnect between what people believe and what they will share on social media, and this is largely driven by inattention rather than by purposeful sharing of misinformation. 
Effective interventions can nudge social media users to think about accuracy, and can leverage crowdsourced veracity ratings to improve social media ranking algorithms.
We synthesize a burgeoning literature investigating why people believe and share false or highly misleading news online. Contrary to a common narrative whereby politics drives susceptibility to fake news, people are ‘better’ at discerning truth from falsehood (despite greater overall belief) when evaluating politically concordant news. Instead, poor truth discernment is associated with lack of careful reasoning and relevant knowledge, and the use of heuristics such as familiarity. Furthermore, there is a substantial disconnect between what people believe and what they share on social media. This dissociation is largely driven by inattention, more so than by purposeful sharing of misinformation. Thus, interventions can successfully nudge social media users to focus more on accuracy. Crowdsourced veracity ratings can also be leveraged to improve social media ranking algorithms.

Wednesday, April 07, 2021

How dopamine leads to hallucinations

Hallucinations (perceptual experiences without external stimuli) seen in conditions such as schizophrenia are thought to result from giving too much weight to priors, creating an imbalance at the expense of actual sensory evidence. Sustained high-dopamine tone in the striatum has been proposed to contribute to this imbalance; however, it has remained unclear how the dopaminergic perturbation leads to the generation of hallucinations. Schmack et al. have developed a cross-species computational psychiatry approach to directly relate human and rodent behavior and used this approach to study the neural basis of hallucination-like perception in mice. Here is the summary of their results and their conclusion:   


We set up analogous auditory detection tasks for humans and mice. Both humans and mice were presented with an auditory stimulus in which a tone signal was embedded in a noisy background on half of the trials. Humans pressed one of two buttons to report whether or not they heard a signal, whereas mice poked into one of two choice ports. Humans indicated how confident they were in their report by positioning a cursor on a slider; mice expressed their confidence by investing variable time durations to earn a reward. In humans, hallucination-like percepts—high-confidence false alarms—were correlated with the tendency to experience spontaneous hallucinations, as quantified by a self-report questionnaire. In mice, hallucination-like percepts increased with two manipulations known to induce hallucinations in humans: administration of ketamine and the heightened expectation of hearing a signal. We then used genetically encoded dopamine sensors with fiber photometry to monitor dopamine dynamics in the striatum. We found that elevations in dopamine levels before stimulus onset predicted hallucination-like perception in both the ventral striatum and the tail of the striatum. We devised a computational model that explains the emergence of hallucination-like percepts as a consequence of faulty perceptual inference when prior expectations outweigh sensory evidence. Our model clarified how hallucination-like percepts can arise from fluctuations in two distinct types of expectations: reward expectations and perceptual expectations. In mice, dopamine fluctuations in the ventral striatum reflected reward expectations, whereas in the tail of the striatum they resembled perceptual expectations. We optogenetically boosted dopamine in the tail of the striatum and observed that increasing dopamine induced hallucination-like perception. This effect was rescued by the administration of haloperidol, an antipsychotic drug that blocks D2 dopamine receptors.
We established hallucination-like perception as a quantitative behavior in mice for modeling the subjective experience of a cardinal symptom of psychosis. We found that hallucination-like perception is mediated by dopamine elevations in the striatum and that this can be explained by encoding different kinds of expectations in distinct striatal subregions. These findings support the idea that hallucinations arise as faulty perceptual inferences due to elevated dopamine producing a bias in favor of prior expectations against current sensory evidence. Our results also yield circuit-level insights into the long-standing dopamine hypothesis of psychosis and provide a rigorous framework for dissecting the neural circuit mechanisms involved in hallucinations. We propose that this approach can guide the development of novel treatments for schizophrenia and other psychotic disorders.

Monday, April 05, 2021

A Dendrite-Focused Framework for Understanding the Actions of Ketamine and Psychedelics

I pass on the highlioght points from an interesting review (open source, with a useful graphic) of how the similar therapeutic effects of ketamine and psychedelics might be explained:
Ketamine can relieve symptoms of depression and anxiety, therefore filling a critically unmet psychiatric need. A few small-scale clinical studies suggest serotonergic psychedelics may have similar therapeutic effects.
Ketamine may both enhance and suppress dendritic excitability, through microcircuit interactions involving disinhibition.
Serotonergic psychedelics may both enhance and suppress excitability, through targeting coexpressed receptors.
Spatial mismatch in the opposing drug actions on dendritic excitability is predicted to steer plasticity actions towards certain synapses and cell types.
We present a dendrite-focused framework as a novel lens to view the actions of ketamine and serotonergic psychedelics on cortical circuits.

Thursday, April 01, 2021

False memories can be reversed without damage to true memories.

 Oeberst et al.  demonstrate the effectiveness of source sensitization, which involves alerting participants that their memories could come from external sources, and false memory sensitization, which involves informing individuals that repeatedly being asked to recollect events can produce false memories. The two strategies could be widely implemented in real-world settings and do not require interviewers to know any ground truths.:  


Human memory is fallible and malleable. In forensic settings in particular, this poses a challenge because people may falsely remember events with legal implications that never actually happened. Despite an urgent need for remedies, however, research on whether and how rich false autobiographical memories can be reversed under realistic conditions (i.e., using reversal strategies that can be applied in real-world settings) is virtually nonexistent. The present study therefore not only replicates and extends previous demonstrations of false memories but, crucially, documents their reversibility after the fact: Employing two ecologically valid strategies, we show that rich but false autobiographical memories can mostly be undone. Importantly, reversal was specific to false memories (i.e., did not occur for true memories).
False memories of autobiographical events can create enormous problems in forensic settings (e.g., false accusations). While multiple studies succeeded in inducing false memories in interview settings, we present research trying to reverse this effect (and thereby reduce the potential damage) by means of two ecologically valid strategies. We first successfully implanted false memories for two plausible autobiographical events (suggested by the students’ parents, alongside two true events). Over three repeated interviews, participants developed false memories (measured by state-of-the-art coding) of the suggested events under minimally suggestive conditions (27%) and even more so using massive suggestion (56%). We then used two techniques to reduce false memory endorsement, source sensitization (alerting interviewees to possible external sources of the memories, e.g., family narratives) and false memory sensitization (raising the possibility of false memories being inadvertently created in memory interviews, delivered by a new interviewer). This reversed the false memory build-up over the first three interviews, returning false memory rates in both suggestion conditions to the baseline levels of the first interview (i.e., to ∼15% and ∼25%, respectively). By comparison, true event memories were endorsed at a higher level overall and less affected by either the repeated interviews or the sensitization techniques. In a 1-y follow-up (after the original interviews and debriefing), false memory rates further dropped to 5%, and participants overwhelmingly rejected the false events. One strong practical implication is that false memories can be substantially reduced by easy-to-implement techniques without causing collateral damage to true memories.